A switch device of this type has a switching element provided inside a casing which is operated with an operating knob, and when the operating knob is not operated, the switching element is restored while the operating knob is returned to its original position. The restoring of the switching element and the returning of the operating knob are achieved with elastic returning mechanisms provided therefor.
The returning mechanism for the operating knob is, in general, provided at the lower end portion of an operating member for the switching element. This operating member protrudes downwards from an operating part in such a manner that the returning mechanism is integral with the operating member. For instance, a coil spring is embedded in the lower end portion of the operating member, and a plunger is provided in such a manner that it is urged by the coil spring. The lower end portion of the plunger operates the switching element through a movable piece, and it is returned by its own elastic force while being guided by the movable piece.
In FIG. 7, a related configuration is shown. Reference numeral 101 designates a lower casing. A circuit board 102 is mounted on the lower casing 101, and is covered with an upper casing 103, on which a decorative cover 104 called "bezel" is placed.
A plurality of switching elements 107 are provided on the circuit board 102. More specifically, the switching elements 107 are fixedly secured to the circuit board 102 by soldering their fixing terminals 130 which stick out on the side of the back of the circuit board through through-holes. The upper casing 103 has mounting holes 111 and pivotal supports 112 for switch operating knobs 110 at positions corresponding to those of the above-described switching elements 107. Each of the switch operating knobs 110 has an operating end portion 125 extended downwards. The operating end portion 125 is inserted into the mounting hole 111, and is swingably supported by the support 112. When the switch operating knob 110 is mounted in this way, the lower end of the operating end portion 125 is engaged with a driven part 126 of the switching element 107.
The decorative cover 104 has windows 128 to expose the switch operating knobs 110. That is, the decorating cover 104 is placed over the upper casing 103 in such a manner that the switch operating knobs 110 are positioned at the windows 128, respectively.
When, in the switch device thus constructed, the switch operating knob 110 is operated, its operating end 125 moves the driven part 126 of the switching element 107, thereby to operate the switching element 107.
In the related switch device, as described above, the switching elements 107 are secured to the circuit board 102 by soldering the fixing terminals 130 which stick out on the backside of the circuit board 102. That is, since the fixing terminals protrude from the back of the circuit board 102, it is necessary to provide a clearance C on the backside of the circuit board 102 in an amount equal to the length of protrusion of the fixing terminals, and the thickness of the switch device is increased by as much. In the case of a switch device for a motor vehicle or the like, a space for installation of the switch device is limited. Hence, there has been a strong demand for provision of a switch device which is compact, and small particularly in thickness.
In a switch device for a power seat mounted on a motor vehicle, in order to slide the whole seat back and forth, or to move the front or rear end of a seat cushion vertically, one switch knob is slid parallel or turned about an axis.
FIG. 8 shows a part of another related switch device which includes a switch mechanism 63 which is turned on and off with a switch knob 61. The switch knob 61 is turned in the directions of the arrows I and J, so that a drive piece 62 connected fixedly to the switch knob 61 is turned in the same way, to operate the switch mechanism 63.
For this purpose, a substantially circular hole 64a is formed in a body casing 64 so as to permit the rotation of the drive piece 62, and a groove 62a is formed in the lower surface of the base of the drive piece 62 to transmit the motion of the drive piece 62 to a movable piece 63a of the switch mechanism 63. The groove 62a has a so-called relief so that the movable piece 63a can move linearly in the directions of the arrows K and L.
In order to guide the drive piece 62 and to return the switch knob 61 to the initial position, plungers 62c are elastically supported on the upper surface of the base of the drive piece by springs 62b, while V-grooves 64b are formed in the rear surface of the body casing 64 in such a manner that they are inclined towards the drive piece 62. The V-grooves 64b thus guide the plungers 62c. When the drive piece 62 is turned, it is allowed to return to the original neutral position with the aid of the plungers 62c thus elastically supported.
In the related switch device, as described above, the V-grooves 64b for returning the drive piece 62 are cut in the rear surface of the body casing so that they are inclined, and the plungers 62c supported elastically by the springs 62b are provided below the V-grooves 64b. Hence, the switch device suffers from difficulties that the body casing 64 is unavoidably large in thickness, and the installation of the switch device is limited in place.
Further, in a motor vehicle, a seat switch for a driver's seat is installed, for example, on the right side of the seat, and a seat switch for a passenger side seat is installed on the left side of the seat. These two seat switches are unavoidably different in the configuration of their casings from each other because the way of installing the seat switch on the right side of the seat is different from that of installing the seat switch on the left side of the seat, although their bodies are the same. That is, it is necessary to use two different types of casings which substantially determine the external forms of the seat switches. As a result, the manufacturing cost is increased.